Tuning apparatus



May 28, 1957 R. E. THOMPSON TUNING APPARATUS Filed May 25, 1955 1N VEN TOR.

ala/E f 0732175022 Z MQ lnite tat TUNEN G APPARATUS ReynaldlE. Thompson, Mount Prospect, Iii., assigner to .Motorola, Inc., Chicago, Ill., acorporationnf illinois This invention relates to push button tuning mechanisms for radio receivers, and moreparticularly to a de vice for presetting an adjustable push button structure to `permit repeated selection of a given station.

The locking device of the presentinvention is particularly designed for use in connection with radio tuners Awherein-a cam member supported on a slidably mounted plunger rod may engage a treadle bar `structure including a pair of parallelmembers mounted on a rotatable carriage coupled to tuning elements associated with resonant circuits. In such mechanisms, it is common for the cam member to-be vfixed at a certain angle with Arespect to its supporting plunger rod -so that as therod ismoved with respect to the parallel members, the cam may bring the members into alignment with the surface thereof, thus setting the carriage and Ithe resonant circuits to `the Vproper adjustment for reception of the desired station. It is obviously advantageous to have the position of the cam firmly iixed so that exact tuning may be obtained upon each operation of the plunger rod. Furthermore, it is desirable to incorporate provision for easily changing the setting of the cam so that the receiver may be tuned to any desired frequency by `operation of a plunger rod.

An object of this invention is .to provide an improved compact locking mechanism for a cam-supported on a plunger rod `of a'push button` tuner,.which mechanism furnishes smooth and positiveautomatic releaseand lockingof the `cam bymovementof the .rrodrvvhich` provides station selecting.

Another :object is to provide `a cam locking. mechanism for` a push button tuning plunger requiring `lbutl few-component parts` and whichulocking mechanism.` may be. unlocked `and'lockedby `mere manipulationnoithe push buttons, Aand .in whichoperating forcer applied thereto is `substantially along the Vaxis `of thenplunger'to minimize any tendency` for lateral `movement `of the mechanism.

A feature `.ofthe invention is 4the provision of. aspush button tuner including a plunger, rod and a cam clamping bar pivotally mounted in an .aperture` in the" rodiwith one end ofthe baradapted `to lockstheY cam in position on `one side ofthe plunger rod and the other end ofthe bar having `an arcuate sectionwhich `may be drawnY or constrained toward the other side ofuthe rod to pivot the bar inthe aperture for locking of .the-cam.

A further ,object of i the invention is fthe provision of such clamping ymechanism in whichza rod actuator lmember `is slidablymounted on thenplungerrod` and has `an encircling loop `to engage the arcuate yspring section of the clamping bar as theactuator member is moved. `The plunger rod may also have a `stepped `portion in `which is locatedtheaperture for pivotally supporting the clamping bar so that the unit is compact and force applied to the` actuatoimrnembenis substantially along the axisof ,the plunger rod.

Furtherobjects, `features and the attending advantages Hof the invention mayl be appreciated Vupon;consideratiou 4latent of the following ,description `when taken in conjunction with the accompanying drawing in which:

Fig..1 is a topview of radio tuning apparatus employing the` invention;

locking a cam member on a plunger rod in push button tuning apparatus (for a radio by further movement of the rod in the direction which also provides station selection. The plunger rod is -slidably mounted and carries a cam member rotatably atlixed thereto for engaging and setting a pairot parallel bar members of a treadle bar structure which is part of a carriage linked to variable tuning elements of resonant circuits in the radio receiver. `Anaperture in the plunger rod supports a clamping bar in pivotal relation, .one end of which may clamp the cam in fixed postionon oneside of ,the rod and the other end of which is` arched forming a section which may be drawn toward the plunger rod by a slidable extension of the rod to lockA the mechanism. The slidable extension supports a push button and has .an encircling loop fwhich engages the arched section of the clamping `bar when 'the' plunger rod is pushed inwardly atthe same time the cam is moved against the parallel bar members for tuning purposes. However, when pulled outwardly,` the slidable exten-sion disengages the arched section ofthe clamping bar 'to iree this `bar and thus free the cam so that it may be set at a position for tuning the resonant circuits to a desired station. The above mentioned aperture in the `plunger rod for support of the clamping bar may be in `a stepped portion thereof, in which `case the mechanism is very compact and an operating force applied thereto has little tendency `for bending or jamming the device, since the force is substantially along the axis of the plunger rod.

Reference is now made to the drawings, in connection with which a detailed explanation of the invention will be given. In the tuning apparatus 10, there is included a plurality of slug tuned coil units 12 which are supported by frame 14. The units 12 are incorporated in resonant circuits of a radio receiver circuit as is familiar to those in the art, and the movable slugs 16 thereof are fastened to a slidable portion of carriage 20. Carriage 20` also includes a treadle bar structure having a a pairof parallel bar members 24 which are mounted on a rotatable arm 25 about an axis midway between the bar, members. Link sections y27 connect the slidable portion of carriage 20 to an `extension of the arm 25 so that as members 24 are rotated about their axis, carriage 20 and the slugs 16 attached `thereto are moved to effect tuning of the coil units.

For continuous tuning of the apparatus, a shaft 30 may be turned by a suitable knob atlixed thereto in order to move the carriage 20. A gear system` 32 mechanically joins the shaft 30 through a clutch system 3510 the arm 25 in order to apply the rotary motion of shaft Si) to carriage 20 by what is eliectively a Vernier arrangement. In order to accomplish rapid tuning to particular predetermined frequencies, a series of plunger rods 40-44 is provided. These plunger rods are all of similar con-struction, and only the details of rods 43 Will be explained.

Manual pushing of button 48 inwardly against spring t9 moves cam member 52 to the left in Fig. 2 and moves the bars 24 into alignment with the surface of lthe cam member, thus tuning the apparatus to a certain frequency. Fig. 2 illustrates the position of maximum inward travel of plunger rod 43 where cam 52 has aligned the bar members 24. In order to facilitate the push button operation, clutch mechanism is used to disengage the continuous tuning shaft 30 and the gear reduction system 32. This is accomplished when the end of plunger rod 43 moves against an inclined surface of the release bar 57, which shifts this bar to the right in Fig. 1 against spring 59 so that arm 62 of the release bar opens the clutch mechanism 35. When push button 4S has been released, the spring 49 returns the plunger rod 43 to its position as shown in Fig. l, and spring 59 re-engages the clutch mechanism 35 so that manual tuning by adjustment of shaft 30 is again possible.

The locking mechanism of the invention will now be described in connection with Figs. 2-6. This mechanism is concerned with locking cam 52 in a certain angular relation with respect to plunger rod 43 so that operation of this rod adjusts the tuning slug 16 to tune to a desired frequency. Cam 52 is rotatably mounted on plunger rod 43 by beans of a rivet 65. An aperture 68 in an oiset or stepped portion of the plunger rod 43 supports clamping bar in pivotal relation. It may be noted that one end of clamping bar 75 bears against the cam mem-ber 52 (Fig. 3) and at the other end of clamping bar 75 has an arcuate section 77.

A slidable actuating member 43a constitutes an extension of the plunger rod 43 and is secured thereto by means of the rivet positioned in a slot 82 in the member 43a. Member 43a is slidable in respect to the plunger rod 43 but the movement thereof is restricted by the slot 82 in which the rivet is secured. A spring member 85 is also secured to the device by means of rivet 80 as Well as by a bent-over end portion thereof which engages plunger rod 43 through an aperture 36 therein. A small deformed portion 88 in the spring member 85 is adapted to engage the end of slot 8.2 with the device in locked position, as shown in Fig. 3. When slidable actuating member 43a is moved to the dotted line position of Fig. 3, which will be explained in detail below, the deformed portion 33 of spring member 85 engages a small dent 99 in member 43a to secure the plunger rod 43 and the actuating member 43a in restraining relation. A pair of lugs 92 and 93 extend respectively through slot and 96 in the plunger rod 43 and serve as guides for slidable motion of actuating member 43a with respect to the plunger rod. A part of lug 92 serves as an encircling portion or loop for the arcuate section 77 of the clamping bar 75 as shown in Figs. 3 and 6.

in order to lock the cam member 52 in a, desired position, the mechanism is positioned as shown in the solid lines of Fig. 3. Therefore, lug 92 constrains the arcuate section 77 toward one side of plunger rod 43 so that l clamping bar 75 is pivoted in the aperture '73 and the end of clamping bar 75 secures member 52 to the other side of the plunger rod 43. It may also be seen that pushing plunger rod 43 inwardly in order to tune the apparatus would not tend to change the locked condition of the mechanism since member 43a is stopped when rivet St) engages the end of slot 82. l

ln order to change the setting of the cam member 52, the following operations are carried out. First, the manual tuning shaft 3i) is operated to select a desired frequency to which the apparatus is to be tuned through i operation of the push button which is being adjusted. Then, actuating member 43a is pulled outwardly to the dotted position of 3 so that the raised portion 83 engages the dem 534i and loop 92 disengages the arcuate section 7"! of the clamping bar' 75. This then releases the clamping bar, and the cam member 52 may turn freely. The final step is to push inwardly on the button 43 to bring the cam member 52 against the previously Iset parallelbar members 24 and thereby to allow the freely turning cam member 52 to assume a desired position. Further pushing with greater force would move the actuating member 43a with respect to plunger rod 43 and bring the apparatus to the position shown in the solid lines of Fig. 3. Thus, loop 92 will engage the arcuate section 77 and lock the clamping bar against the cam member 52 in the desired position. The action of spring 85 when portion 88 engages dent 9i) insures that locking will not commence until cam 52 has been properly positioned against bar members 24.

This invention provides, therefore, a locking mechanism especially adapted for securing a cam member on a plunger rod in a desired angular relation therewith. The device may be easily set by merely pulling outwardly on the actuating member, after tuning to a desired station, and then operating the associated plunger rod in the usual fashion, which locks the mechanism so that it may be used for rapidly retuning to that selected station. It may be seen that the apparatus is compact, and that the stepped portion of the plunger rod leaves space on both sides of the rod in which other parts of the mechanism may be disposed. Furthermore, since the apparatus is confined to a rather small cross-section, force upon the actuator member 43a will be largely applied along the axis of the plunger rod so that there will be little tendency to cause lateral movement. Accordingly the mechanism is of sturdy construction and provides smooth positive operation.

l claim:

l. In mechanism for locking one member with respect to another, the combination of an elongated member having an aperture therein, a member to be locked supported on said elongated member adjacent said aperture, a clamping bar pivotally supported in said aperture and having a rst end on one side of said elongated member adapted to engage said member to be locked for xedly clamping the same to said elongated member, said clamping bar also having a second end on the other side of said elongated member including a portion spaced from said elongated member, and slidable means for drawing said second end toward said elongated member to pivot said bar in said aperture into engagement with said member to be locked for fixing the same with respect to said elongated member.

2. In mechanism for locking one member with respect to another, the combination of an elongated member having an aperture therein, a cam member rotatably mounted on said elongated member with a surface thereof adjacent said aperture, a clamping bar pivotally supported in said aperture and having a first end on one side of said elongated member adapted to engage said surface of said cam member for clamping the same to said elongated member, said clamping bar also having a second end on the other side of said elongated member comprising an arched portion spaced from said elongated member, and slidable means supported on said one side of said elongated member having a loop portion encircling said arched portion for drawing the same toward said elongated member to pivot said bar in said aperture and bring the same into engagement with said cam member for locking the same with respect to said elongated member.

3. In mechanism for locking one member with respect to another, the combination of a plunger rod having a stepped section therein and an aperture in said stepped section, a cam member rotatably mounted on said plunger rod adjacent said stepped section and having a first surface contiguous to said plunger rod and a second surface opposite and parallel to said rst surface, a clamping bar pivotally supported in said vaperture with portions extending on opposite sides of said plunger rod, said clamping bar having a first end adapted to engage said second surface for clamping said cam member to one side of said plunger rod, said clamping bar also having a second end comprising an arched portion spaced from the other side of said plunger rod, and slidable'means supported by said plunger rod for drawing said arched portion thereto to pivot said clamping bar into engagement with said cam member for locking the same with respect to said plunger rod.

4. In radio tuning means including a push rod structure carrying a cam thereon for controlling the position of tuning elements, with the cam being rotatably mounted on the push rod structure and adapted to be locked in position and released therefrom in response to relative movement between first and second parts of the push rod structure; the combination including an elongated member having an intermediate transverse portion with an aperture therein, said elongated member forming the first part of the push rod structure, a cam rotatably mounted on said member adjacent said transverse portion, a clamping bar pivotally supported on said elongated member and extending through said aperture therein, said clamping bar having iirst and second ends extending on opposite sides of said member, said first end of said clamping bar being positioned to engage said cam, said second end ot said clamping bar being spaced from said elongated member, and a slide member forming the second part of the push rod structure and being slidably mounted with respect to said elongated member, said slide member having a portion adapted to engage said second end of said clamping bar to draw the same toward said elongated member and thereby press said rst end of said clamping bar against said cam to hold the same with respect to said elongated member.

5. In radio tuning means including a push rod structure carrying a cam thereon for controlling the position of tuning elements, with the cam being rotatably mounted on the push rod structure and locked in position and released therefrom in response to relative movement between first and. second parts of the push rod structure, an elongated member having first and second parallel portions connected by an intermediate off-set portion, said elongated member forming the first part of the push rod structure, a cam rotatably mounted on said rst portion on the side thereof toward said second portion, said off-set portion of said member having an aperture therein, a

clamping bar pivotally supported on said elongated meniber and extending through said aperture thereof, said clamping bar extending between said rst and second parallel portions and having first and second ends extending on opposite sides of said member, said rst end of said clamping bar being positioned to engage said cam, and a slide member forming the second part of the push rod structure slidably mounted on said second portion of said elongated member, said slide member having a portion adapted-to engage said second end of said clamping bar to draw the same toward said elongated member and thereby press said first end of said clamping bar against said cam to hold the same with respect to said elongated member.

6. In mechanism for locking one member with respect to another, the combination of an elongated member having an off-set portion therein with an aperture in said ottset portion, said off-set portion forming iirst and second stepped sections of said elongated member, a member to be locked with respect to said elongated member supported adjacent said aperture, a clamping bar pivotally supported in said aperture and having a first end extending along said first stepped section of said elongated member and being engageable with said member to be locked, said clamping bar also having a second end extending along said second stepped section of said elongated member, said second end being spaced from said elongated member, and slidable means supported on said elongated member and having an encircling portion adapted to draw said second end of said clamping bar toward said elongated member upon operations to a tirst position for clamping said member to be locked by pivotal movement of said clamping bar in said aperture, with operation of said slidable means to a second position causing disengagement of said encircling portion from said second end bf lsaid clamping bar for releasing said member to be oc ed.

References Cited in the le of this patent UNITED STATES PATENTS 2,489,544 Schwartz etal. Nov. 29, 1949 

